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CHAPTER EIGHT

THE BLOOD VASCULAR SYSTEM

The heart, arteries, capillaries and veins comprise the blood vascular system. It is important that we know something about this system since it is the means by which blood is circulated to all parts of the body, and blood as we know, is an exceedingly important constituent of the human body. With an abundance of it, rich and free of contamination, we are able to enjoy health; without it in ample healthy quantity, we are easy victims of disease.

THE HEART- This is a hollow cone shaped organ situated in the chest above the diaphragm, slightly left of the center and between the lungs. It is about the size of the clenched fist and weighs from ten to twelve ounces. It is composed of muscular tissue whose cells are branched and connected with one another in an interlocking network called CARDIAC MUSCLES. These muscles belong to the involuntary class. The heart is divided from the point to the base by a partition forming a right and left half. Each half is subdivided into an upper cavity called the AURICLE,and a lower cavity called the VENTRICLE. The heart then has four chambers, (1) right auricle, (2) right ventricle, (3) left auricle, (4) left ventricle. The right side of the heart contains blood from the veins, or VENOUS blood and the left side ARTERIAL blood, or blood for the arteries. Each auricle empties blood into the ventricle beneath it through openings known as VALVES. But the auricles do not connect, nor do the ventricles.

ARTERIES
The arteries are hollow tubes that carry blood FROM the heart to all parts of the body. The walls of these tubes are thick, strong and elastic. The largest arteries in the body are the AORTA and the PULMONARY, which measure about 1 1/4 inches in diameter where they join the right and left ventricles of the heart. The Pulmonary artery (right) carries venous

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[[caption]] DIAGRAM OF THE HEART [[/caption]]

TEXT BOOK OF BEAUTY CULTURE

blood to the lungs and back to the left auricle; the Aorta (left) immediately after leaving the heart begins to divide and subdivide into smaller branches called ARTERIOLES and these in turn diminish into minute vessels called CAPILLARIES. When arteries lose their power of elasticity they are said to have grown hard, hence persons so afflicted are said to have hardening of the arteries, (ARTERIO-SCLEROSIS).

CAPILLARIES
The capillaries are hair like tubes that connect the smallest arteries with the smallest veins. They are very abundantly distributed in a close network throughout all the body tissue except the cartilages, hair, nails, cuticle and parts of the eye. The work of the capillaries is most important for it is through their thin walls that nutrition is supplied the cells and waste products are collected. It is in the capillaries that the chief work of the blood is done. Everywhere, throughout the body, through their walls an interchange takes place which is essential to life. In many parts of the body the capillaries are so numerous that a pin point cannot be inserted between them. They are most abundant in the organs of secretion and absorption.

THE VEINS
The veins are collapsible tubes formed by the uniting of capillaries. They carry the blood BACK TO the heart. The main differences between the veins and arteries are that veins are not as elastic as arteries, many of the veins have valves, or membranous pockets which cling tightly to the walls and prevent any backward flow of the blood, and the walls of veins are much thinner than the walls of arteries. The arteries do not collapse when empty, but the veins when emptied of blood by injury or accident immediately collapse.
The functions of the blood vessels are to carry pure blood containing nutritive agents (food and oxygen) to all parts of the body, to carry impure blood from the tissues of the organs for purification and to convey the secretions of the various glands.

BLOOD
Blood is a somewhat sticky fluid, slightly heavier than water that circulates through the heart and blood vessels. It has a faint peculiar ordor, salty taste and is slightly alkaline. It is estimated to constitute about one-sixteenth of the weight of the